System and Method for Electrosurgical Conductive Gas Cutting for Improving Eschar, Sealing Vessels and Tissues

ABSTRACT

An electrosurgical method and device for simultaneously cutting and coagulating tissue with an electrosurgical device having an electrode and a channel wherein said channel has a port near a proximal end of said electrode, wherein the method comprises the steps of causing an inert gas to flow through said channel and exit said port, applying high-frequency energy to said electrode while said inert gas flows through said channel, wherein said high-frequency energy applied to said electrode continuously plasmatizes inert gas exiting said port, initiating an electrical discharge from said electrode through said continuously plasmatized inert gas to said tissue, cutting tissue with said electrode, maintaining said electrical discharge from said electrode through said plasmatized inert gas while cutting tissue with said electrode to cause coagulation of said tissue simultaneously with said cutting.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to U.S. Provisional PatentApplication Ser. No. 61/409,138 filed by the present inventors on Nov.2, 2010 and U.S. Provisional Patent Application Ser. No. 61/550,905filed by the present inventors on Oct. 24, 2011.

The aforementioned provisional patent application is hereby incorporatedby reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

BACKGROUND OF THE INVENTION

1. Field Of The Invention

The present invention relates to electrosurgical systems and methods,and more particularly, electrosurgical systems and methods using argonplasma during cutting modes of operation.

2. Brief Description Of The Related Art

The standard means for controlling traumatic and surgical blood loss areelectrosurgical generators and lasers which respectively directhigh-frequency electrical currents or light energy to localize heat inbleeding vessels so as to coagulate the overlying blood and vesselwalls. Hemostasis and tissue destruction are of critical importance whenremoving abnormal tissue during surgery and therapeutic endoscopy. Formonopolar electrosurgery electrical energy originates from anelectrosurgical generator and is applied to target tissue via an activeelectrode that typically has a small cross-sectional surface-area toconcentrate electrical energy at the surgical site. An inactive returnelectrode or patient plate that is large relative to the activeelectrode contacts the patient at a location remote from the surgicalsite to complete and electrical circuit through the tissue. For bipolarelectrosurgery, a pair of active electrodes are used and electricalenergy flows directly through the tissue between the two activeelectrodes.

U.S. Pat. No. 4,429,694 to McGreevy disclosed a variety of differentelectrosurgical effects that can be achieved depending primarily on thecharacteristics of the electrical energy delivered from theelectrosurgical generator. The electrosurgical effects included purecutting effect, a combined cutting and hemostasis effect, a fulgurationeffect and a desiccation effect. Fulguration and desiccation sometimesare referred to collectively as coagulation.

A conventional desiccation procedure, shown in FIG. 1B, typically isperformed by holding the active electrode in contact with the tissue.Radiofrequency (RF) current passes from the electrode directly into thetissue to produce heating of the tissue by electrical resistanceheating. The heating effect destroys the tissue cells and produces anarea of necrosis spreading radially from the point of contact betweenthe electrode and the tissue. The necrosis is usually deep.

A conventional fulguration procedure, shown in FIG. 1A, may be obtainedby varying the voltage and power applied by the electrosurgicalgenerator. Conventional fulguration procedures typically were performedusing a waveform which has a high peak voltage but a low duty cycle. Ifthe active electrode was brought close to but not touching the tissueand the peak voltage was sufficient to produce an RF arc, fulgurationwould occur at the point where the arc contacted the tissue. Due to thelow duty cycle, the power per unit time applied to the tissue was lowenough so that cutting effects were minimized.

A conventional cutting procedure, shown in FIG. 1C, may be obtained bydelivering sufficient power per unit time to the tissue to vaporize cellmoisture. If the power applied is high enough a sufficient amount ofsteam is generated to form a steam layer between the active electrodeand the tissue. When the steam layer forms, a plasma consisting ofhighly ionized air and water molecules forms between the electrode andthe tissue. An RF arc then develops in the plasma. At the location wherethe arc contacts the tissue, the power density becomes extremely highand instantaneously disrupts the tissue architecture. New steam isthereby produced to maintain the steam layer. If the power density issufficient, enough cells are destroyed to cause a cutting action tooccur. A repetitive voltage wave form, such as a sinusoid, delivers acontinuous succession of arcs and produces a cut with very littlenecrosis and little hemostasis.

It also was possible to create a combined combination of effects byvarying the electrical waveform applied to the tissue. Specifically, acombination of conventional cutting and desiccation could be produced byperiodically interrupting the continuous sinusoidal voltage typicallyused to perform a conventional cutting procedure. If the interruptionwas sufficient, the ionized particles in the plasma between theelectrode and the tissue would collapse, causing the electrode tomomentarily come into contact with the tissue. That touching woulddesiccate the tissue thereby sealing off blood vessels in the vicinityof the electrode.

Conventional electrosurgical generators typically have both “cut” orcutting and “coag” or coagulation modes of operation. As previouslynoted, the cut mode typically will have a low voltage waveform form witha high duty cycle, e.g. 100%. The coag mode of an electrosurgicalgenerator typically creates a waveform with large amplitude but shortduration “spikes” to achieve hemostasis (coagulation). For example, incoag mode an electrosurgical generator may use a high voltage wave format a 6% duty cycle. The surrounding tissue is heated when the waveformspikes and then cools down (between spikes), producing coagulation ofthe cells. Fulguration is achieved in the coag mode of theelectrosurgical generator, with the tip of the surgical “activeelectrode” held above (but not in contact with) the tissue.Electrosurgical desiccation is achieved in either the cut or coag modesof the generator. The difference between desiccation and fulguration isthe tip of the “active electrode” must contact the tissue as in FIG. 1Bin order to achieve desiccation. Typically, the more desired mode toachieve tissue desiccation through direct tissue contact is the cutmode. Different degrees of hemostasis (coagulation) can be achieved byutilizing varying degrees of “Blended” waveforms, e.g., 50% on/50% off,40% on/60% off, or 25% on/75% off.

Another method of monopolar electrosurgery via argon plasma technologywas described by Morrison U.S. Pat. No. 4,040,426 in 1977 and McGreevyU.S. Pat. No. 4,781,175. This method, referred to as argon plasmacoagulation (APC) or argon beam coagulation is a non-contact monopolarthermoablative method of electrocoagulation that has been widely used insurgery for the last twenty years. In general, APC involves supplying anionizable gas such as argon past the active electrode to target tissueand conducting electrical energy to the target tissue in ionizedpathways as non-arcing diffuse current. Canady described in U.S. Pat.No. 5,207,675 the development of APC via a flexible catheter thatallowed the use of APC in endoscopy. These new methods allowed thesurgeon, endoscopist to combine standard monopolar electrocautery with aplasma gas for coagulation of tissue.

APC has been demonstrated to be effective in the coagulation of bloodvessels and human tissue during surgery. APC functions in a noncontactmanner. The electrical current is initiated only when the tip of thehandpiece or catheter is within one centimeter of the target tissue andproduces a homogenous 1 mm to 2 mm well-delineated eschar. The escharcreated by APC is further characterized by a decrease absence ofcharring and carbonization compare to eschar resulting from conventionalelectrosurgical fulguration. The eschar remains firmly attached to thetissue, in contrast to other coagulation modalities where there is anoverlying charred layer of coagulated blood. There is minimal tissuenecrosis with APC.

In U.S. Pat. Nos. 5,217,457 and 5,088,997 to Delahuerga et al. discloseda device for performing procedure referred to as “argon shrouded cut.”The device was an electrosurgical pencil having an exposed electrodewith a distal end defining a tip for cutting biological tissue and anose piece mounted about the electrode to define a pathway for a streamof inert gas which shrouds the electrode at or near its tip. When incoagulation mode, a convergent stream of inert gas was directed directlyonto the tip of the electrode. In coagulation mode, the voltage wassufficient to initiate an electrical discharge in the inert gas. In cutmode, the stream of ionized gas was directed to impinge obliquely on theelectrode at a point adjacent to but away from the tip of the electrode.In cutting mode, the open circuit voltage was generally not high enoughto continuously plasmatize the inert gas and initiate and maintain anelectrical discharge. Accordingly, in cut mode the function of the inertgas is to provide a shroud around the electrode rather than to initiateelectrical discharge.

A multitude of literature exists that discloses and discusses variouscommercially available electrosurgical generators and the voltagewaveforms produced by those generators. For example, A. Erwine,“ESU-2000 Series Product Overview A Paradigm Shift in ElectrosurderyTesting Technology and Capability Is Here,” BC Group International, Inc.(2007) describes electrosurgical generators from ERBE ElektromedizinGmbH and ConMed Corporation, among others.

SUMMARY OF THE INVENTION

In a preferred embodiment, the present invention is an electrosurgicalmethod for simultaneously cutting and coagulating tissue with anelectrosurgical device having an electrode and a channel wherein saidchannel has a port near a proximal end of said electrode for directing agas onto said proximal end of said electrode. The method comprises thesteps of causing a gas to flow through said channel and exit said port,applying high-frequency energy to said electrode while said gas flowsthrough said channel, wherein said high-frequency energy applied to saidelectrode continuously plasmatizes gas exiting said port, initiating anelectrical discharge from said electrode through said continuouslyplasmatized gas to said tissue, cutting tissue with said electrode,maintaining said electrical discharge from said electrode through saidplasmatized gas while cutting tissue with said electrode to causecoagulation of tissue adjacent said proximal end of said electrodesimultaneously with said cutting. The gas may comprise an inert gas suchas argon. The step of applying high-frequency energy to said electrodemay comprise applying 70-100 W of power to said electrode. The step ofcausing a gas to flow through said channel may comprise causing an inertgas to flow through said channel at a flow rate of 7 L/min. Theelectrosurgical device is connected to an electrosurgical generator,said generator having a cut mode comprising a repeating voltage waveformand a coag mode comprising a varying voltage waveform, and wherein saidstep of applying high-frequency energy to said electrode comprisesactivating said electrosurgical generator in said cut mode. Therepeating voltage waveform maY be a sinusoidal waveform. The inert gasmay exit the port in a direction substantially parallel to saidelectrode. A portion of said channel adjacent said port in said channelmay be held at an angle of 45° to 60° to a surface of target tissue. Thesimultaneously cutting and coagulating causes a low depth of injury tosaid tissue and a small diameter of injury to said tissue.

In another embodiment, the present invention is an electrosurgicaldevice. The device comprises means for initiating an electricaldischarge from an electrode through continuously plasmatized inert gasto tissue and means for simultaneously cutting tissue with an energizedelectrode and coagulating said tissue by maintaining said electricaldischarge from said electrode through said plasmatized inert gas whilecutting said tissue with said energized electrode. The means forsimultaneously cutting tissue and coagulating said tissue using aplasmatized inert gas may comprise a housing having an opening at adistal end, an electrode extending from said distal end of said housing,a channel within said housing, said channel having a port adjacent saidelectrode extending from said housing, means for causing an inert gas toflow through said channel and exit said port, means for applyinghigh-frequency energy to said electrode while said inert gas flowsthrough said channel, wherein said high-frequency energy applied to saidelectrode continuously plasmatizes inert gas exiting said port, meansfor initiating an electrical discharge from said electrode through saidcontinuously plasmatized inert gas to said tissue, and means formaintaining said electrical discharge from said electrode through saidplasmatized inert gas while cutting tissue with said electrode to causecoagulation of said tissue simultaneously with said cutting. Theelectrosurgical device may further comprising telescoping nozzleconnected to said housing, wherein said telescoping nozzle is adjustableto change a length of said electrode extending from said housing. Theelectrode extends 2-25 mm from said telescoping nozzle.

In a preferred embodiment, the electrosurgical device comprises ahousing, an electrode, wherein the electrode extends through the housingand a portion of the electrode extends from a distal end of the housing,a connector for connecting the electrode to an electrosurgicalgenerator, a channel in the housing, a port at a proximate end of thechannel for connecting the channel to a source of pressurized inert gas,and a port at a distal end of the channel for discharging inert gasflowing through the channel, and controls for initiating a flow of aninert gas through the channel and applying high-frequency electricalenergy to the electrode, wherein the controls provide for a conventionalcut mode, a conventional coagulation mode, an argon plasma coagulationmode, and a plasma cut mode. The plasma cut mode comprises maintainingan electrical discharge from the electrode through plasmatized inert gasbeing discharged from the channel while cutting tissue with theelectrode to cause coagulation of the tissue simultaneously with thecutting.

In one embodiment, the controls comprise three buttons in the housingfor allowing operating the device in the cut mode, the conventionalcoagulation mode, the argon plasma coagulation mode, and the plasma cutmode. In another embodiment, the controls comprise a footswitch forallowing operating the device in the cut mode, the conventionalcoagulation mode, the argon plasma coagulation mode, and the plasma cutmode. The simultaneously cutting and coagulating may cause a low depthof injury to the tissue. It may also cause a small diameter of injury tothe tissue. The flow rate of the inert gas through the channel may bebetween 0.1 and 10 L/min.

Still other aspects, features, and advantages of the present inventionare readily apparent from the following detailed description, simply byillustrating preferable embodiments and implementations. The presentinvention is also capable of other and different embodiments and itsseveral details can be modified in various obvious respects, all withoutdeparting from the spirit and scope of the present invention.Accordingly, the drawings and descriptions are to be regarded asillustrative in nature, and not as restrictive. Additional objects andadvantages of the invention will be set forth in part in the descriptionwhich follows and in part will be obvious from the description, or maybe learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and theadvantages thereof, reference is now made to the following descriptionand the accompanying drawings, in which:

FIG. 1A is a diagram illustrating a conventional fulguration mode ofoperation of an electrosurgical device.

FIG. 1B is a diagram illustrating a conventional desiccation mode ofoperation of an electrosurgical device.

FIG. 1C is a diagram illustrating a conventional cutting mode ofoperation of an electrosurgical device.

FIG. 2A is a perspective view of an electrosurgical handpiece having itselectrode retracted within its housing in accordance with a firstpreferred embodiment of the present invention.

FIG. 2B is a perspective view of an electrosurgical handpiece having itselectrode extending out from a distal end of its housing in accordancewith a first preferred embodiment of the present invention.

FIG. 2C is an assembly drawing of an electrosurgical handpiece inaccordance with a first preferred embodiment of the present invention.

FIG. 3A is a diagram illustrating an experimental setup for testing inargon coagulation mode.

FIG. 3B is a diagram illustrating an experimental setup for testing apreferred embodiment of the present invention in hybrid plasma cut mode.

FIG. 4A is a graph of pig's liver sample temperature and spark length asfunction of power with a USMI SS-200E/Argon 2 system in conventionalcoagulation mode.

FIGS. 4B-C are tables of the numerical values corresponding to the graphin FIG. 4A.

FIG. 5A is a graph of pig's liver sample temperature as function ofpower at various argon flow rate settings with a USMI SS-200E/Argon 2system in argon plasma coagulation mode.

FIG. 5B is a graph of pig's liver sample temperature as function ofargon flow rate at various power settings with a USMI SS-200E/Argon 2system in argon plasma coagulation mode.

FIG. 5C is a graph of argon beam length as function of power at variousargon flow rate settings with a USMI SS-200E/Argon 2 system in argonplasma coagulation mode.

FIG. 5D is a graph of argon beam length as function of argon flow rateat various power settings with a USMI SS-200E/Argon 2 system in argonplasma coagulation mode.

FIGS. 5E-F are tables of the numerical values corresponding to thegraphs in FIGS. 5A-D.

FIG. 6A is a graph of pig's liver sample temperature as function ofpower performed with a USMI SS-200E/Argon 2 system in conventional cutmode.

FIG. 6B is a table of the numerical values corresponding to the graph inFIG. 6A.

FIG. 7A is a graph of pig's liver sample temperature as a function ofpower at various flow rates performed with a USMI SS-200E/Argon 2 systemin hybrid plasma cut mode in accordance with the present invention.

FIG. 7B is a graph of pig's liver sample temperature as a function ofgas flow rate at various power settings performed with a USMISS-200E/Argon 2 system in hybrid plasma cut mode in accordance with thepresent invention.

FIG. 7C is a table of numerical values corresponding to the graphs inFIGS. 7A and 7B.

FIG. 8A is a graph of pig's liver sample temperature and spark length asfunction of power with a USMI SS-601MCa/Argon 4 system in conventionalcoagulation mode.

FIGS. 8B-C are tables of the numerical values corresponding to the graphin FIG. 8A.

FIG. 9A is a graph of pig's liver sample temperature as function ofpower at various argon flow rate settings with a USMI SS-601MCa/Argon 4system in argon plasma coagulation mode.

FIG. 9B is a graph of pig's liver sample temperature as function ofargon flow rate at various power settings with a USMI SS-601MCa/Argon 4system in argon plasma coagulation mode.

FIG. 9C is a graph of argon beam length as function of power at variousargon flow rate settings with a USMI SS-601MCa/Argon 4 system in argonplasma coagulation mode.

FIG. 9D is a graph of argon beam length as function of argon flow rateat various power settings with a USMI SS-601MCa/Argon 4 system in argonplasma coagulation mode.

FIGS. 9E-F are tables of the numerical values corresponding to thegraphs in FIGS. 9A-D.

FIG. 10A is a graph of pig's liver sample temperature as function ofpower performed with a USMI SS-601MCa/Argon 4 system in conventional cutmode.

FIG. 10B is a table of the numerical values corresponding to the graphin FIG. 10A.

FIG. 11A is a graph of pig's liver sample temperature as a function ofpower at various flow rates performed with a USMI SS-601MCa/Argon 4system in hybrid plasma cut mode in accordance with the presentinvention.

FIG. 11B is a graph of pig's liver sample temperature as a function ofgas flow rate at various power settings performed with a USMISS-601MCa/Argon 4 system in hybrid plasma cut mode in accordance withthe present invention.

FIG. 11C is a table of numerical values corresponding to the graphs inFIGS. 11A and 11B.

FIG. 12A is a tissue image illustrating depth of injury of 1.2 mm at apower setting of 20 W with a USMI SS-200E/Argon 2 system in conventionalcut mode.

FIG. 12B is a tissue image illustrating depth of injury of 1.5 mm at apower setting of 20 W with a USMI SS-200E/Argon 2 system in conventionalcoagulation mode.

FIG. 12C is a tissue image illustrating depth of injury of 0.1 mm at apower setting of 20 W and a flow setting of 0.1 l/min. with a USMISS-200E/Argon 2 system in hybrid plasma cut mode.

FIG. 12D is a tissue image illustrating depth of injury of 0.6 mm at apower setting of 20 W a flow setting of 0.5 l/min. with a USMISS-200E/Argon 2 system in argon plasma coagulation mode.

FIGS. 13A and 13B are a table and graph of conventional cut data with aUSMI SS-200E/Argon 2 system.

FIGS. 14A and 14B are a table and graph of conventional coagulation datawith a USMI SS-200E/Argon 2 system.

FIGS. 15A and 15B are a table and graph of argon plasma coagulation datawith a USMI SS-200E/Argon 2 system.

FIGS. 16A and 16B are a table and graph of hybrid plasma cut data with aUSMI SS-200E/Argon 2 system in hybrid plasma cut mode in accordance witha preferred embodiment of the present invention.

FIGS. 17A and 17B are a table and graph of hybrid plasma cut data with aUSMI SS-601MCa/Argon 4 system in hybrid plasma cut mode in accordancewith a preferred embodiment of the present invention.

FIG. 18A is a table of depth of injury data with a USMI SS-200E/Argon 2system in conventional cut mode.

FIG. 18B is a table of depth of injury data with a USMI SS-200E/Argon 2system in conventional coagulation mode.

FIG. 18C is a table of depth of injury data with a USMI SS-200E/Argon 2system in argon coagulation mode.

FIG. 18D is a table of depth of injury data with a USMI SS-200E/Argon 2system in hybrid plasma cut mode in accordance with a preferredembodiment of the present invention.

FIG. 18E is a table of depth of injury data with a USMI SS-601MCa/Argon4 system in hybrid plasma cut mode in accordance with a preferredembodiment of the present invention.

FIG. 19A is a graph comparing depth of injury data for a USMISS-200E/Argon 2 system in argon plasma coagulation mode and in hybridplasma cut mode.

FIG. 19B is a graph comparing depth of injury data for a USMISS-200E/Argon 2 system in hybrid plasma cut mode and a USMISS-601MCa/Argon 4 system in hybrid plasma cut mode.

FIG. 19C is a graph comparing depth of injury data for a USMISS-200E/Argon 2 system in conventional cut mode, conventionalcoagulation mode, argon plasma coagulation mode with a gas flow rate of2.5 l/min and in hybrid plasma cut mode with a gas flow rate of 2.5l/min.

FIG. 19D is a graph comparing depth of injury data for a USMISS-200E/Argon 2 system in conventional cut mode, conventionalcoagulation mode, argon plasma coagulation mode with a gas flow rate of5 l/min and in hybrid plasma cut mode with a gas flow rate of 5 l/min.

FIG. 20A is a graph of depth of injury data for a USMI SS-200E/Argon 2in argon plasma coagulation mode.

FIG. 20B is a graph of depth of injury data for a USMI SS-200E/Argon 2in hybrid argon cut mode in accordance with a preferred embodiment ofthe present invention.

FIG. 20C is a graph of depth of injury data for a USMI SS-601MCa/Argon 4system in hybrid argon cut mode in accordance with a preferredembodiment of the present invention.

FIG. 21A is a tissue image of in vivo porcine skin Hybrid Plasma cut 20w@3 liters/min, 2 sec., depth of injury 0.2 mm, eschar 1.5 mm.

FIG. 21B is a tissue image of in vivo skin Conventional Cut: 20 w@3liters/min, 2 sec. depth of injury (0.4 mm), eschar (2.5 mm).

FIG. 21C is a tissue image of in vivo Conventional Coagulation: 20 w@3liters/min, 2 sec., depth of injury (3.4 mm), eschar (5.0 mm).

FIG. 21D is a tissue image of Argon Plasma Coagulation: 20 w@ 3liters/min, 2 sec., depth of injury 2.0 mm, eschar 5.0 mm.

FIG. 21E is a tissue image of Argon Plasma Coagulation: depth of injury(1.0 mm), eschar (10.0 mm) @40 w, 3 liters/min.

FIG. 21F is a tissue image of in vivo Hybrid Plasma cut: depth of injury(0.2 mm), Eschar (1.4 mm), 40 w@3 Liters/min.

FIG. 21G is a tissue image of in vivo porcine resection of 1^(st) partof Duodenum with Hybrid plasma cut, depth of Injury (0.2 mm) eschar (1.0mm) @ 40 w, 3 liters/min, 3 sec.

FIG. 21H is a tissue image of in vivo porcine resection of Sternum:depth of injury 0.6 mm, 120 w@ 5 liters/min.

FIGS. 21I and 21J is a tissue image of in vivo resection of sternum invivo porcine model minimal bone marrow damage (0.2 mm) @120 w, 5liters/min.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of an electrosurgical device 100 in accordancewith the present invention is described with reference to FIGS. 2A-2C.The electrosurgical device, handpiece or pencil 100 has a rigid housing110 and telescoping nozzle or tip 120. The rigid housing may be formed,for example, from molded sides 102 and 104. The two sides 102, 104 arejoined to form housing 110 having a hollow chamber within. Within thehousing 110 is an electrode 230, electrode tubing 270 and a fiberglassplate 240. The electrode 230 extends through the electrode tubing 270.The electrode tubing additional has within it a channel, tube or othermeans for conducting the inert gas from the distal end of tubing 220through the electrode tubing 270 and out of the electrode tubing 270.The inert gas leaving the channel in the electrode tubing then passesout of an opening at the distal end of the nozzle 120. The fiberglassplate 240 and electrode 230 are connected to electrical cable assembly210. The electrode tubing is connected at its distal end to the hosetubing 220. An O-ring is placed between the telescoping nozzle and theelectrode tubing to form a seal therebetween. A ceramic tip 250 may beplaced at a distal end of the telescoping tip or nozzle 120 to protectthe nozzle 120 from heat damage where the electrode passes through anopening at the distal end of the nozzle 120. The electrical cableassembly extends from a proximal end of the housing 110 and has at itsdistal end a plug 212. During operation of the device, the connector 212is connected to an electrosurgical generator. The PVC hose tubing alsoextends from the proximal end of the housing 110 and has at its distalend a gas connector body 222, a gas connector tip 224 and an O-ring 226.During operation of the device, the gas connector assembly (222, 224,226) is connected to a source of an inert gas such as argon.

The housing 110 has a plurality of opening or holes for accommodating aplurality of controls or buttons 140, 150, 160. The telescoping nozzleor tip 120 has a control element 122 extending through a slot 112 in thehousing 110. The control element, tab, know or slider 122 is used by asurgeon to move the telescoping tip 120 into or out of an opening in adistal end of the housing 120. Three controls or buttons 140, 150, 160,extend out of openings in the housing 110 and have springs 152 betweenthem and fiberglass plate or connected 240 to bias the controls orbuttons away from the plate or connector 240.

The electrosurgical device of the present invention can be operated, forexample, in four different modes: conventional cut mode, conventionalcoagulation mode, argon plasma coagulation mode, and hybrid plasma cutmode. The eschar resulting from cutting and coagulation in the hybridplasma cut mode in accordance with the present invention issubstantially better than conventional fulguration, cutting and argonplasma coagulation techniques. In addition there is substantial absenceof charring, carbonization, tissue necrosis and destruction of adjacenttissue. Thus, tissue can be precisely cut and the adjacent vesselssimultaneously sealed with minimal depth of injury, tissue necrosis,eschar and carbonization.

An inert gas combined with high-frequency energy in the plasma cut modecan precisely cut through tissues (i.e. skin, muscle, bone or vascular)with substantial speed and accuracy.

Any generator that provides high-frequency voltage to ionize the inertgas to form a gas stream can be used. Preferred generators include theCanady Plasma™ Electrosurgery Unit model (SS-601 MCa) and the CanadyPlasma™ Electrosurgery Unit model (SS-200E) that are preferably usedwith the Argon plasma units Canady Plasma™ Argon 4 Coagulator (CPC 4)and Canady Plasma™ Argon 2 Coagulator (CPC 2), respectively. The CPC 4provides a controlled flow of inert gas to the electrosurgical deviceduring argon plasma coagulation mode and in hybrid plasma cut mode. Theflow rate and the power can be manually set. In a coagulation mode, thegenerator delivers, for example, a peak-to-peak voltage of less than9000 volts. In a cut mode, for example, the generator delivers apeak-to-peak voltage of less than 3800 volts. Most preferably, apeak-to-peak voltage of 100 to 9000 volts is delivered by the generator.

Any accessory devices can be attached to the electrosurgery unit/plasmaunit combination. Exemplary devices are an electrosurgical device (ahandpiece) or an argon plasma flexible probe (catheter), rigid orlaparoscopic.

For operating the electrosurgical device, high-frequency current can beactivated by two push buttons for the conventional cut mode and theconventional coagulation mode, respectively. Argon gas may be deliveredby activating a third push button. This activation will allow the argonplasma coagulation mode and the hybrid plasma cut mode. The plasma cutmode will cut and coagulate the tissue at the same time. It can beeasily switched between the different modes by activating the respectivebuttons. The plasma or electrical current can also be activated by afootswitch.

The telescoping nozzle of the electrosurgical device can be extended orshortened over the electrode as desired when performing plasmaprocedures. In a preferred embodiment, the electrode extends 2 to 25 mmoutside the telescoping nozzle.

The electrode can be of any common material of the state of the art. Ina preferred embodiment, the electrode is a tungsten wire.

In a preferred embodiment, the present invention is an electrosurgicalmethod for achieving cutting and coagulating simultaneously with asource of inert, ionizable gas in combination with high-frequencyenergy. The source of inert, ionizable gas can be any kind of inert,ionizable gas. The preferred type of gas for use in cutting is pureargon. Argon gas causes a decrease in tissue temperature which limitsmicro-destruction of tissue, improves through conductivity of tissue andallows high-frequency cutting through tissue at low tissue temperatures.Inert gas also dissipates oxygen molecules from the surgical area andprevents oxidation of tissue which causes decrease local tissuetemperature and prevents carbonization. Flow rates can vary and can beadjusted depending on the tissue that is being cut.

A high-frequency current supplied by an electrosurgical generator istransmitted through an electrode. Electrodes can be composed, forexample, of tungsten, stainless steel, ceramic or any electricalconducting material. An electrical discharge is created between theactive electrode and the tissue. The discharge is ignited by AC voltagewith a typical amplitude and frequency at 4 kV and or greater than 350kHz respectively. The voltage waveform preferably is a sinusoidalwaveform that contains alternate positive and negative sections ofapproximately equal amplitudes. An inert gas flows through the channelcontaining the electrode. The electrode contacts the tissue and deliversan ionized plasma high-frequency current through the tissue. A newphenomenon has been created by the present invention, which canprecisely cut through the tissue and simultaneously seal adjacentvessels and tissue with.

The present invention is further evidenced by the following examples.

Ex Vivo Porcine Model

All ex vivo porcine experiments were carried out on explant porcineliver samples @ Micropropulsion and Nanotechnology Laboratory (MpNL),George Washington University, Washington, D.C. and WEM EquipamentosPlasma Research Laboratory, Ribeirao Preto-Sao Paulo, Brazil. Liversamples were immediately placed in 10% formalin solution ph 7.0 and sentfor H & E preparation of the pathological slides and interpretation atLaboratorio de Patologia Cirurgica Dr Prates, Ribeirao Preto-Sao Paulo,Brazil

In Vivo Porcine Model

In vivo porcine surgical operations were performed at the University ofSao Paulo, Department of Surgery and Anatomy, Animal ResearchLaboratory, Ribeirao Preto, S P, Brazil. Approval was obtained by theinstitution animal research director. Three dalland female swine (meanweight 14.5 kg) were used in this study. Anesthesia was induced withketamine 50 mg/cc mixed and dopaser—xilazina 200 mg/10 cc,intramuscular. Animals were then intubated, and anesthesia wasmaintained with Na Pentathol to effect. The skin was prepped withalcohol and draped in the usual sterile manner. Mercedes, abdominalmidline, and median sternotomy were made during the operations with theplasma scalpel. Multiple surgical procedures were performed mediansternotomy, gastric resection, partial splenectomy, partial nephrectomy,partial hepatectomy, wedge resection of the liver, intestinal resectionand skin incisions. Operations were video-recorded. Observations ofsurgical bleeding during the procedure were recorded. Depth of injuryand eschar was compared with four high frequency operations modes:conventional cut and coagulation, argon plasma coagulation and hybridargon plasma cut. Samples of the skin, liver, stomach, intestine, andbone were placed in 10% formalin solution ph 7.0 and sent for H & Epreparation of the pathological slides and measurement of depth ofinjury and diameter of eschar at Laboratorio de Patologia Cirurgica DrPrates, Ribeirao Preto-Sao Paulo, Brazil. Animals were sacrificed byusing an intravenous injection of pentobarbital sodium and phenytoinsodium.

The hybrid plasma scalpel blade of the present invention was used incombination with USMI's SS-200E/Argon 2 and SS-601MCa/Argon 4 toevaluate in four high frequency operation modes: (i) conventional cut;(ii) conventional coagulation; (iii) conventional argon plasmacoagulation (APC); and (iv) hybrid plasma cut. As described above in thebackground of the invention, conventional cut and coagulation modes donot involve the use of an inert gas such as argon. Instead, they areperformed by touching the target tissue with the active electrode.Conventional argon plasma coagulation is performed as it was describedabove in the background of the invention. The hybrid plasma cut mode isthe mode of the present invention described above in the detaileddescription of the preferred embodiments. The hybrid plasma scalpel usedin all four modes is as described above with respect to FIGS. 2-C.

Four parameters were measured: plasma discharge column length, tissueheating, diameter of eschar and depth of injury by high frequencyoperation mode. The length of the plasma was characterized by themaximal length of the discharge plasma column observed at tissuetreatment with the hybrid plasma scalpel at which the discharge can besustained. The treatments were video-recorded by digital camera NikonCoolpix 995 (15 frames/s) and the maximal length of discharge plasmacolumn (L) was measured by post-experiment evaluation of recordedvideos. The tissue heating was characterized by the temperature growth(ΔT) of pig's liver sample appeared as result of application of hybridplasma scalpel. ΔT was measured using the thermocouple (Type K) probesembedded in the pig's liver. The accuracy of temperature and lengthmeasurements were 5° C. and 0.5 mm respectively. Tissue temperatureprior to treatment was 18-20° C. Eschar diameter produce by the plasmascalpel blade was measured using a digital caliber. Pathologists used anMotim Camera 1000, 1.3 an Olympus Microscope Bx 41 to calculate thedepth of injury.

The pig's liver samples were treated by the hybrid plasma scalpel asfollowing. In coagulation mode, the pig's liver sample was treated by 5consecutive applications of the hybrid plasma scalpel to the same pointof the liver sample (total treatment duration was ˜5 s). Thethermocouple was located about 3 mm under the treated point as shown inFIG. 3A. In cut mode, a 5 mm straight cut in the pig's liver sample wascreated by five consecutive passes with hybrid plasma scalpel along thecut (total duration ˜5 s) and thermocouple probe was located about 3 mmaside from the cut (see FIG. 3B). The hybrid plasma scalpel was usedwith both the Argon 2/SS-200E and Argon 4/SS601MCa systems with flowrates from 0.5 to 5 liters/minute and from 0.1, 3.0, 7.0 and 10.0liter/minute respectively. Data and graphs of results from theseexperiments are shown in FIGS. 4-11 and 13-20 and images of the treatedtissue are shown in FIGS. 12A-D and 21A-J.

Data and graphs for testing of each of the four operating modes areshown in the drawings as follows: i) conventional cut shown in FIGS.6A-6B, 10A-B, 13A-B and 18A; (ii) conventional coagulation shown inFIGS. 4A-C, 14A-B and 18B; (iii) conventional argon plasma coagulationshown in FIGS. 5A-F, 9A-F, 15A-B and 18C; and (iv) hybrid plasma cutshown in FIGS. 7A-C, 11A-C, 16A-B, 17A-B (with Argon 4/SS601MCa), 18Dand 18E (with Argon 4/SS601MCa). Graphs comparing performance in thevarious modes of operation are shown in the graphs in FIGS. 19A-D and20A-C.

FIGS. 19C-D show comparisons of the depth of injury found in the fourmodes of operation performed with the Argon 2/SS-200E system. FIG. 19Cshows the comparison with both the conventional argon plasma coagulationmode and the hybrid plasma cut mode of the present invention at an argonflow rate of 2.5 L/min. FIG. 19D showsn the comparison using an argonflow rate of 5 L/min. One can see form FIG. 19C that at lower powersettings, e.g., below 70 W, and a flow rate of 2.5 L/min., the hybridplasma cut mode of the present invention results in the depth of tissueinjury being greater than the depth of injury in conventional argonplasma coagulation mode. Since the electrosurgical generator is in acutting mode similar to (or identical to) conventional electrosurgicalcutting when the hybrid plasma cut mode of the present invention isused, it is logical that it would result in a greater depth of injurythan a conventional argon plasma coagulation mode. At mid to high powerranges, e.g. 70-100 W (see item 1920), however, the hybrid plasma cutmode of the present invention results in a smaller depth of injury thanconventional argon plasma coagulation and conventional electrosurgicalcutting. The result is vastly superior to conventional electrosurgicalcutting (0.7-1.5 mm depth for hybrid plasma cut versus 2.5-3.7 mm forconventional cut) and significantly better than conventional APC (0.6 mmfor plasma cut versus 1.2 mm for conventional APC). FIG. 19D showssimilar results for an argon flow rate of 5 L/min. In lower power ranges(see item 1940) the depth of injury for hybrid plasma cut tends to trackthe depth of injury with conventional electrosurgical cutting. In mid tohigh power ranges, e.g., 70-100 W (see item 1930), however, the hybridplasma cut mode of the present invention provides superior, i.e.,smaller, depth of injury versus both conventional argon plasmacoagulation (see item 1930) and conventional electrosurgical cutting.FIGS. 19A shows a comparison of the depth of injury in the hybrid argoncut mode of the present invention versus the conventional argon plasmacoagulation mode at argon flow rates of 2.5 and 5.0 L/min. The graph inFIG. 19A shown that with the Argon 2/SS-200E system, the hybrid plasmacut mode of the present invention achieves a substantially superiorresult compared to conventional argon plasma coagulation at settings ofabout 70-90 W and 2.5 L/min (see item 1902) and 30-50 W at 5 L/min (see1904). FIG. 19B shows a comparison of the hybrid plasma cut mode of thepresent invention performed with the two different test systems. In FIG.19B, one can see that with the Argon 4/SS601MCa system, the hybridplasma cut mode of the present invention achieves an unexpectedlysuperior result at settings of about 50-80 W and 7 L/min (see item 1910)but also is superior to conventional APC in the power range of 50-100 Wat 7 L/min.

As shown in FIG. 20A, the depth of injury associated with conventionalargon plasma coagulation is not very dependent upon the argon flow rate.As each power level tested on the Argon 2/SS-200E system in conventionalAPC mode, the depth of injury varied only by a small amount(approximately <2 mm) at each flow rate tested. In contrast, in thehybrid plasma cut mode of the present invention, significant variationsin the depth of injury were found at various combinations of power andargon flow rate as shown in FIGS. 20B and 20C. In FIG. 20B, it can beseen that at higher power levels of 60-100 W on the Argon 2/SS-200Esystem in hybrid plasma cut mode, the depth of injury decreasesdramatically in the argon flow rate range 2020 of 1-3 L/min at a powerlevel of 100 W decreases steadily as the flow rate increases up the 5L/min., which was the highest flow rate tested on that system. With thatsystem, the graph in FIG. 20B shows a particular beneficial effect at apower level of about 80 W and an argon flow rate of about 2.5 L/min. InFIG. 20C, it similarly can be seen that at higher power levels of 60-100W on the Argon 4/SS601MCa system in hybrid plasma cut mode the depth ofinjury decreases dramatically in the argon flow rate range 2030 of 6-8L/min. In can be seen in the graph of FIG. 20C that with this morepowerful system, a particularly beneficial effect is achieved with powerlevels of 60-100 W and an argon flow rate of approximately 7.0 L/min.

The foregoing description of the preferred embodiment of the inventionhas been presented for purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed, and modifications and variations are possible in lightof the above teachings or may be acquired from practice of theinvention. The embodiment was chosen and described in order to explainthe principles of the invention and its practical application to enableone skilled in the art to utilize the invention in various embodimentsas are suited to the particular use contemplated. It is intended thatthe scope of the invention be defined by the claims appended hereto, andtheir equivalents. The entirety of each of the aforementioned documentsis incorporated by reference herein.

What is claimed is:
 1. An electrosurgical method for simultaneouslycutting and coagulating tissue with an electrosurgical device having anelectrode and a channel wherein said channel has a port near a proximalend of said electrode for directing a gas onto said proximal end of saidelectrode, the method comprising the steps of: causing a gas to flowthrough said channel and exit said port; applying high-frequency energyto said electrode while said gas flows through said channel, whereinsaid high-frequency energy applied to said electrode continuouslyplasmatizes gas exiting said port; initiating an electrical dischargefrom said electrode through said continuously plasmatized gas to saidtissue; cutting tissue with said electrode; maintaining said electricaldischarge from said electrode through said plasmatized gas while cuttingtissue with said electrode to cause coagulation of tissue adjacent saidproximal end of said electrode simultaneously with said cutting.
 2. Theelectrosurgical method of claim 1, wherein said gas comprises an inertgas.
 3. The electrosurgical method of claim 1 wherein step of applyinghigh-frequency energy to said electrode comprises applying 70-100 W ofpower to said electrode.
 4. The electrosurgical method of claim 3wherein step of causing a gas to flow through said channel comprisescausing an inert gas to flow through said channel at a flow rate of 7L/min.
 5. The electrosurgical method of claim 1, wherein saidelectrosurgical device is connected to an electrosurgical generator,said generator having a cut mode comprising a repeating voltage waveformand a coag mode comprising a varying voltage waveform, and wherein saidstep of applying high-frequency energy to said electrode comprisesactivating said electrosurgical generator in said cut mode.
 6. Theelectrosurgical method of claim 5, wherein said repeating voltagewaveform comprises a sinusoidal waveform.
 7. The electrosurgical methodof claim 1, wherein said electrode comprises a tungsten wire.
 8. Theelectrosurgical method of claim 1, wherein said step of initiating anelectrical discharge from said electrode through said continuouslyplasmatized inert gas to said tissue comprises placing said electrodeless than 1 cm from said tissue.
 9. The electrosurgical method of claim1, wherein said inert gas exits said port in a direction substantiallyparallel to said electrode.
 10. The electrosurgical method of claim 1,wherein a portion of said channel adjacent said port in said channel isat an angle of 45° to 60° to a surface of target tissue.
 11. Theelectrosurgical method of claim 1, wherein the simultaneously cuttingand coagulating causes a low depth of injury to said tissue.
 12. Theelectrosurgical method of claim 1, wherein the simultaneously cuttingand coagulating causes a small diameter of injury to said tissue.
 13. Anelectrosurgical device comprising: means for initiating an electricaldischarge from an electrode through continuously plasmatized inert gasto tissue; and means for simultaneously cutting tissue with an energizedelectrode and coagulating said tissue by maintaining said electricaldischarge from said electrode through said plasmatized inert gas whilecutting said tissue with said energized electrode.
 14. Anelectrosurgical device according to claim 13, wherein said means forsimultaneously cutting tissue and coagulating said tissue using aplasmatized inert gas comprises: a housing having an opening at a distalend; an electrode extending from said distal end of said housing; achannel within said housing, said channel having a port adjacent saidelectrode extending from said housing; means for causing an inert gas toflow through said channel and exit said port; means for applyinghigh-frequency energy to said electrode while said inert gas flowsthrough said channel, wherein said high-frequency energy applied to saidelectrode continuously plasmatizes inert gas exiting said port; meansfor initiating an electrical discharge from said electrode through saidcontinuously plasmatized inert gas to said tissue; means for maintainingsaid electrical discharge from said electrode through said plasmatizedinert gas while cutting tissue with said electrode to cause coagulationof said tissue simultaneously with said cutting.
 15. An electrosurgicaldevice according to claim 13, further comprising telescoping nozzleconnected to said housing, wherein said telescoping nozzle is adjustableto change a length of said electrode extending from said housing. 16.The electrosurgical device of claim 15, wherein the electrode extends2-25 mm from said telescoping nozzle.
 17. The electrosurgical device ofclaim 13, wherein said inert gas comprises argon.
 18. An electrosurgicaldevice comprising: a housing; an electrode, wherein said electrodeextends through said housing and a portion of said electrode extendsfrom a distal end of said housing; a connector for connecting saidelectrode to an electrosurgical generator; a channel in said housing; aport at a proximate end of said channel for connecting said channel to asource of pressurized inert gas; and a port at a distal end of saidchannel for discharging inert gas flowing through said channel; andcontrols for initiating a flow of an inert gas through said channel andapplying high-frequency electrical energy to said electrode, whereinsaid controls provide for a conventional cut mode, a conventionalcoagulation mode, an argon plasma coagulation mode, and a plasma cutmode; wherein said plasma cut mode comprises maintaining an electricaldischarge from said electrode through plasmatized inert gas beingdischarged from said channel while cutting tissue with said electrode tocause coagulation of said tissue simultaneously with said cutting. 19.The electrosurgical device of claim 18, wherein said controls comprisethree buttons in said housing for allowing operating the device in saidcut mode, said conventional coagulation mode, said argon plasmacoagulation mode, and said plasma cut mode.
 20. The electrosurgicaldevice of claim 18, wherein said controls comprise a footswitch forallowing operating the device in said cut mode, said conventionalcoagulation mode, said argon plasma coagulation mode, and said plasmacut mode.